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Full text of "The Cambridge Natural History"

552

ORIGIN  OF LEMURS

)ne  of these   early forms is referred to the  genus Mixodectes, a
jenus which  has  been placed, though with a query, in the order
ilodentia.     It   appears,   however,   to   be a  Lemuroid, and   is  of
Lnierican   range.     The  incisor  teeth  have   been   held   to  argue
hat it lies on the  direct track of Cfairomys ;  but other features,
lore  especially the form  of the  astragalus,  have been used  to
rgue the justice of the inclusion of this type within the order
lodentia.     Allied, as  it  is  supposed, to   this form, is Ividrodon,
Iso of the lowest Eocene deposits of the United States.    Indrodon
icdaris  is   known   from   fragments   of  nearly  all   parts   of  the
tceleton.    They indicate the existence of a creature of about one-
alf the   size   of Lemur varius.     It   had   slender   limbs   and   a
rag and  powerful  tail.     The  humerus, as  in  so  many archaic
easts,  has   an  entepicondylar  foramen.     The  femur   has  three
rochanters, and the fibula articulates with the astragalus.     It is
ot  always  easy  to  distinguish  these primitive  mammals from
ich other, so that the  minutest of characters have to be called
i to our assistance.     One of the contemporaneous groups with
hich   these   early   Lemurs  might   be   confused   is that  of  the
ondylarthra ; it is important, therefore, to note that in. Indrodon
le calcaneo-cuboidal articulation is nearly flat, and not bent as
is in  the former  group.     The teeth are  of the tritubercular
ittern.     The  incisors  are  not  known, but the molars and pre-
.olars are  each  three.     To the  same  family, which   has  been
armed AnaptomorpMdae, is referred the genus Awaptomorpkus,
hich   has   been   specially   compared   to   Tar&ius.     This   small
limal has a Xamurine face  with huge orbits.     It has a pre-
.olar  less   than   Jndrodon.     It   has   been   ascertained   that   -<4.
jmunculus had an external lachrymal foramen.1
Another family, that of the Ckriacidae, appear to hover on
le border line of Lemurs and Creodonts, having been referred to
>th by various palaeontologists. Professor Scott suggests their
Bmurine or at least Primate relationships, while Cope urged
teir Greodont affinities. A difficulty raised by Scott was, that
i Chriacus the premolars of the lower jaw were spaced. But it
>pears that this is not fatal to their inclusion in the Primates,
nee Tomitherium, an " undoubted Primate," shows the same
ature. If Chria&us is a Lemur it is an earlier type than those
* See Schlosser, JBeitrage Pal. Osterr. Mwnff. 1888 ; also Osbom and Earle, SulL
mer. Mus* JVot* ICist. vii. 1895, p. 16.